Why does my 4yr old hate Jews?

My son came into the kitchen this morning and said, "Daddy, I hate the Jews at my school." I was immediately mortified. "What on earth? " I thought, as my mind began to race. Has he said this to another child or a teacher and if so, am I going to be tagged as a racist by the other pre-school parents? Maybe some child is picking on him? No,no,no... that's nonsense ....if anything - he'd be the bully. OMG! That's even worse. What have I done? Have I spawned a little skinhead?Then I went into logic mode. "How does my 4 yr old discern religious differences at this age?" Surely there aren't 4 yr olds at his school dressed in scarves, yarmuls and kippahs. Wait, wait,...focus Dave... let's get to the bottom of this. I knelt down and placed my hands on my son's shoulders and in a gentle fatherly tone I asked, " Son, ... why do you hate the Jews at your school?" His reply...... " 'Cause it's sour and it makes the cookies taste bad."